JPH03163561A - Color toner - Google Patents

Abstract

PURPOSE:To stabilize performances against uses for a long time and against changes of environmental conditions by using specified alumina particles as external additives of the color toner. CONSTITUTION:The alumina particles to be used as the external additives of the color toner have a saturated water content QL of >=1.5wt.% at 15 deg.C and a relative humidity of 10% and that QH of <=12wt.% at 32.5 deg.C and 85%, and QH/QL<=3, and a specific surface area SB measured by the BET method is 30 - 300m<2>/g. The alumina particles function as a sort of spacer, as a result, forms parts low in electric chargeability on the surfaces of the toner particles and weaken the attaching force of the toner particles to each other and alleviate direct contact between the toner particles and carrier surfaces, thus permitting high-quality images to be stably obtained for a long period.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to electrophotography. The present invention relates to a color toner for visualizing an electrostatic latent image in an image forming method such as electrostatic recording.

[Prior Art] In recent years, as image forming apparatuses such as electrophotographic color copying machines have become widespread, their uses have expanded to a wide variety of uses, and demands on their image quality have become stricter. When copying images such as general catalogs and maps, down to the minute details,
There is a need for extremely detailed and faithful reproduction without distortion or breakage.

In recent years, in image forming apparatuses such as electrophotographic color copying machines that use digital image signals, the latent image is formed by a collection of dots with a constant potential, and solid areas. Halftone and light areas are expressed by changing the dot density. However, if the toner particles do not adhere to the dots faithfully and the toner particles protrude from the dots, the gradation of the toner image that corresponds to the ratio of dot densities in the black and white areas of the digital latent image cannot be obtained. There is a problem. Furthermore, when improving resolution by reducing the dot size in order to improve image quality, it becomes even more difficult to reproduce the latent image formed from minute dots, and the resolution and especially the gradation of highlight areas become more difficult. Images tend to have poor quality and lack sharpness.

In response to the above-mentioned problems, the present inventors have made studies to reduce the particle size of toner and to improve the faithful reproducibility of latent images made of minute dots.

However, as the particle size of toner is made finer, the cohesiveness of the toner itself increases, and its miscibility with carrier decreases.
Alternatively, a problem arises in that the fluidity of the toner decreases, and in addition, as the particle size of the toner becomes smaller, the specific surface area of the toner increases, so the amount of charge becomes excessive during contact charging with the carrier, resulting in a low concentration. New problems such as transfer problems and transfer defects arise.

Today, in this research field, polyester-based resins are widely used as binders for color toners due to their high negative chargeability and excellent fixing properties, but in general, resins such as polyester are There is an urgent need to develop a better toner that is not affected by environmental changes, as it is easily affected by temperature and humidity, and problems such as an excessive amount of charging system under low temperature and low humidity, and an insufficient amount of charge under high temperature and high humidity are likely to occur. It becomes.

In this way, when trying to further reduce the particle size of toner,
There are many problems to be faced, among which improvement of charging characteristics is essential, and this is the most important point in toner development. [Problems to be Solved by the Invention] An object of the present invention is to provide the following color toner.

■Performance is stable even after long periods of use and environmental changes.

(2) Forms images with high image density and excellent resolution, highlight gradation, and fine line reproducibility, especially in image forming apparatuses using digital image signals.

- Excellent transferability and high image density can be obtained with low consumption.

[Means and effects for solving the problems] The present invention provides a color toner containing at least non-magnetic colorant-containing resin particles containing a polyester resin as a binder resin and an external additive. It contains at least alumina particles as an agent, and the alumina particles have a temperature/humidity=15°C/1
Saturated water content QL at 0% is 1.5% by weight or more, 32.5
The saturated water content QH at °C/85% is 12% by weight or less, the ratio of QH, QL is Q-/QL≦3, and the specific surface area S3 by the BET method is 30 to 300 m''/g. This is a color toner with special characteristics.

When low-charging inorganic oxides such as alumina particles are externally added to the toner, they function as a kind of baser in the frictional charging between the carrier and the toner, resulting in the formation of sites with low charging ability on the toner surface, resulting in the amount of charge on the toner. Curb excess. In addition, it also has the effect of relatively lowering the negative nature of negatively chargeable polyester toner, and is useful for improving charging characteristics.

Therefore, when trying to reduce the particle size of toner, it is essential to use a low-chargeable inorganic oxide such as alumina particles.

Additionally, when toner particles are made smaller, the Coulomb force and van der Waals force that act on the toner become relatively stronger compared to gravity and inertial force, which increases the adhesion between toner particles and makes toner aggregates more likely to form. Although this tends to be the case, alumina particles function effectively to weaken the adhesion force between toners, making it difficult to form toner aggregates.

Furthermore, in order to reduce the direct contact between the toner base and the carrier surface, the toner is transferred to the carrier surface. It is also useful for venting and extends the life of the developer.

As mentioned above, alumina particles are very effective in preventing toner agglomeration and suppressing excessive charging, but the present invention also found that there is a correlation between the water content of alumina particles and charging characteristics. As a result, further improvement in charging characteristics has been achieved.

That is, the water content QL of alumina particles left at low temperature and low humidity (15°C, 10%) for 10 days by heating loss measurement method is 1.
5% by weight or more, under high temperature and high humidity (32.5℃, 8
5%) for 10 days was water content QH of 12% by weight or less. The ratio of QL is QH/
Even better charging characteristics can be obtained when alumina particles satisfying QL≦3 are externally added to colorant-containing resin particles.

In the present invention, by externally adding alumina particles, (1) a region with low charging ability is formed on the so-called toner surface where it does not come into direct contact with the carrier due to contact charging with the carrier;
Alternatively, (2) alumina particles have a strong weak positive property in terms of charging series, so they adhere to the negatively charged polyester toner surface and relatively weaken the negative charging property, especially at low temperatures and low humidity. We have thought that the function is to suppress excessive charge amount, but in our study, we found that (1) above
, In addition to (2), we have found that (3) the part where the alumina particles are adsorbed on the toner surface becomes a kind of leak point and suppresses excessive charge amount. Specifically, crystal defect sites of alumina particles used in the present invention or adsorption sites where water molecules are adsorbed serve as leak points and function to suppress excessive charge amount obtained by contact charging with carriers. do. In other words, it was concluded that the higher the water content of the alumina particles used, the more active sites there are in the alumina particles, and the greater the above effects.

Therefore, under low temperature and low humidity conditions (15°C, 10%), when externally adding alumina particles to toner to reduce the amount of charge on the toner, alumina particles with a high water content are more preferable. It is desirable that the water content QL after standing for 10 days is at least 15% by weight or more. In the case of alumina particles with a large surface area such as those used in the present invention, the QL is 1.5% by weight or more in most cases and there is no particular problem, but in the case of alumina particles subjected to hydrophobization treatment, the QL is 1.5% by weight. If there are no grooves, charge-up will occur in the minute areas where the toner and alumina particles are in contact, making it impossible to achieve the desired tribodown.

As mentioned above, under low temperature and low humidity conditions, alumina particles with a high water content are more advantageous in suppressing excessive toner charge, but under high temperature and high humidity conditions (32.5°C, 85%), On the other hand, if the tribo is too low, problems such as toner scattering and fogging inside the machine are likely to occur. In particular, if the QH exceeds 12% by weight, the triboelectric charge will drop significantly and toner scattering will become severe. In addition Q
If I{>12% by weight, the fluidity of the developer will deteriorate slightly, and new problems such as troubles during toner replenishment and poor mixing and agitation within the developing device will likely occur. Therefore, the water content of alumina particles is QL of 1.5% by weight or more,
Preferably, QH is 12% by weight or less.

For example, it is added to toner for problems such as those mentioned above. If the amount of alumina particles is reduced, it may be possible to reduce scattering even if the alumina particles have a QH exceeding 12%. However, when trying to simultaneously achieve tribodown under low temperature and low humidity conditions, reducing the amount of alumina particles added will obviously increase the tribodown.
In the end, it becomes impossible to obtain balanced charging properties in both environments.

Therefore, in order to obtain a balanced amount of charge in both environments, it is necessary to have a certain amount of water content in low temperature and low humidity conditions, which actively works to suppress the amount of charge, and in high temperature and low humidity conditions. It is sufficient to use alumina particles that satisfy both of these two points: the water content does not change much even if left in a humid environment (water is difficult to adsorb), and the triboelectricity does not drop significantly. The inventors Qo
．． We have found that when alumina particles with a QL ratio of QH/QL≦3 are used, the toner's charging properties become more stable. In other words, if QH/QL is larger than 3, the alumina particles also have the characteristic of easily adsorbing water, and therefore there is a large difference in the water content under both environments. The effect of reducing triboelectric charge becomes even more pronounced under high temperature and high humidity conditions, resulting in the problem of an enlarged difference in the amount of charge between the two environments.

As mentioned at the beginning, the binder used in the present invention is a polyester resin, and there are problems with an excessive amount of charge under low temperature and low humidity conditions and insufficient triboelectricity under high temperature and high humidity conditions.
By adopting alumina particles with H/QL≦3,
We have now provided a toner with higher environmental stability.

As mentioned above, alumina particles are very effective in preventing toner agglomeration and suppressing excessive charging, but these particles have a BET specific surface area SR of 30 m2 for the reasons described below.
'/g (approx. 40mμ) ~300m"/g (approx. 5
mμ), more preferably ao
m”/g (approximately 25 mμ) ~15Qm'/g (approximately 15
mμ) range.

For example, alumina particles with a BET specific surface area larger than 300 m"/g have sufficient fluidity, but the disadvantage is that the toner tends to deteriorate easily due to its hydrophilic nature. Deterioration is caused by the increase in toner consumption. In a state of little
When copying continues, this phenomenon appears as a large change in the amount of charge or a worsening of the fluidity of the developer.

In addition, with alumina particles having a BET specific surface area smaller than 3 om"/g, it is difficult to obtain sufficient fluidity even when used in combination with other fluidity imparting agents. Also, the fluidity imparting agent is insufficiently dispersed. This tends to cause fogging in the image.

Moreover, even if it is in the range of 30 to 300a+2/g, adverse effects are likely to occur if it is not used in combination with hydrophobic silica. 30-1
In the range of 00m27H, the use of alumina particles alone will result in insufficient fluidity, so it is necessary to use them together with hydrophobic silica, which has a high fluidity imparting effect. Furthermore, 100 to 30
In the range of 0 m'/g, the surface of the colorant-containing fine particles can be uniformly covered, but if only low-charging Album particles are used, the amount of charge tends to be extremely low. Therefore, it is necessary to use it together with negatively charged hydrophobic silica.

As mentioned above, in terms of negative chargeability and fluidity imparting ability,
Hydrophobic silica serves to supplement the low charge inorganic oxide. Therefore, a sufficient effect cannot be obtained unless the BET specific surface area is 80o+27g or more. More preferably 15 hours
'/g or more is better. Furthermore, when alumina particles and hydrophobic inorganic oxides are used together, compared to when each is used alone,
The fluidity of the toner is improved, and the mixing properties of the developer and the cleaning properties of the toner are also improved. In order to make the present invention more effective, the specific surface area of the hydrophobic inorganic oxide A should be set to SA
, When the specific surface area of the alumina particles B is Sa, SA is Sa, and A and B are a weight % and b weight %, respectively, with respect to the colorant-containing resin particles, so that they satisfy the following formula: a≧ It is necessary to contain b and 0, 3≦a+b≦1.5.

When a<b or (a+b) is outside the above range, it becomes difficult to maintain a balance between chargeability and fluidity.

Furthermore, if (a+b)>1.5, the fixing properties as a color toner will deteriorate, and in particular, the permeability of traben will decrease. The hydrophobic inorganic oxide used in the present invention is 80m27
Any negative chargeable inorganic oxide having a specific surface area of 1.5 g or more and an absolute value of triboelectric charge with magnetic particles of 50 μc/g or more is acceptable, but as a preferable example, gas phase oxidation of a silicon halogen compound is acceptable. Examples include treated silica fine powder obtained by subjecting the silica fine powder produced by hydrophobization treatment. In the treated silica fine powder, it is particularly preferable that the C silica fine powder is treated so that the degree of hydrophobicity measured by a methanol titration test is in the range of 30 to 80. It is applied by reaction or chemical treatment with an organosilicon compound that physically adsorbs.

In a preferred method, fine silica powder produced by vapor phase oxidation of a silicon halide is treated with an organosilicon compound.

Examples of such organosilicon compounds are hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane,
Allyl phenyldichlorosilane, benzyldimethylchlorosilane, prommethyldimethylchlorosilane, α-chloroethyltrichlorosilane, ρ-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilylmercabutane, trimethylsilylmercabutane, triorganosilyl Acrylate, vinyldimethylacetoxysilane, dimethylethoxysilane, dimethyldimethoxysilane, diphenyldiethoxysilane,
Hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane, and Si containing 2 to 12 siloxane units per molecule, one each for the terminally located unit. Examples include dimethylborisiloxane containing a hydroxyl group bonded to . These may be used in one type or in a mixture of two or more types.

The particle size of the treated silica fine powder is 0. 003~0
．． It is preferable to use one in the range of 1p. Commercially available products include Taranox 500 (Talco Co., Ltd.) and AEROSIL R-972 (Nippon Aerosil Co., Ltd.).

On the other hand, there are no particular restrictions on the manufacturing method or crystal structure of alumina particles, but alumina particles obtained by the vapor phase method generally have a sharp particle size distribution, and the particle size can be controlled relatively easily. It is preferable in that it is also possible to use the toner, and the dispersibility on the toner surface is also good. Further, alumina particles obtained by a wet method may be used as long as the specific surface area is 30 to 300 m''/g, preferably 80 to 150 m2/g, and the water content is within the above-mentioned range.

The so-called wet manufacturing methods of high-purity alumina that are widely used today include the thermal decomposition of ammonium alum,
Various methods have been put into practical use, such as the organic ammonium hydrolysis method, the ethylene chlorohydrin method, the underwater spark discharge method, and the ammonium aluminum carbonate thermal decomposition method, but they all have the same chemical structure due to differences in starting material firing temperature, time, etc. Even alumina particles have very different properties depending on the manufacturer, and in particular, the agglomeration form and primary particle diameter of alumina particles tend to be extremely different due to differences in manufacturing methods.

The alumina particles used in the present invention are preferably those that are not agglomerated, or those that are easy to loosen even if they are agglomerated, and if the alumina particles contain so-called "clumps" that are strongly agglomerated, they are uniformly dispersed on the toner surface. This is not very preferable because it is difficult to control the toner and the charging stability between the toners is deteriorated.

It is also not preferable for the particles to have an extremely angular or acicular shape.

The purity of the alumina particles used in the present invention is not particularly critical as long as they are fine and uniform in particle size, and there is no problem as long as they are generally referred to as high-purity alumina.

Also, alumina particles are amorphous and α due to their different crystal structures.
,γ. Many types such as η, ζ, and σ types are known, but there is no particular limitation as long as the specific surface area by BET method is within the range of 30 to 300 m27H. However, the so-called α-type alumina, which is commonly called alumina, has a small surface area and relatively large particle size, so intermediate alumina with a fine particle size, such as the γ-type, is preferable.

Alumina is obtained by firing aluminum hydroxide or aluminum salt, but it is said that it goes through various processes depending on the starting materials and firing conditions, and ultimately becomes α-type alumina. Therefore, alumina other than α-type is called intermediate alumina or transition alumina, but intermediate alumina such as γ-type has an unstable crystal structure and a high surface area, so it has the characteristic of easily absorbing water. ．． As mentioned above, the higher the water content of the alumina used in the present invention, the greater the effect of lowering tribo. Under low temperature and low humidity conditions, alumina with a high water content is preferable, and the high activity of alumina is important. Again, γ
It can be said that the one type functions more effectively than the alpha one type.

However, even if α-type alumina is used, if the particle size is made extremely fine through some kind of crushing process, its dispersibility on the toner surface will increase, and as a result, it will function to suppress excessive charge amount. Therefore, in the present invention, α-
It does not specify the abundance ratio or mixing ratio of alumina and γ-alumina.

Further, for alumina, etc., which has a particularly high water content under high temperature and high humidity conditions, some kind of hydrophobic treatment may be applied to the surface.

As the binder resin used in the colorant-containing resin particles of the present invention, a polyester resin is first required.

Although polyester resin has excellent fixing properties and is suitable for color toners, it has strong negative charging ability and tends to be overcharged. However, when polyester resin is used in the composition of the present invention, the disadvantages are alleviated and an excellent color toner can be produced. is obtained.

In particular, the following formula (wherein R is ethylene or propylene group, x, y
are each an integer of 1 or more, and the average value of x+y is 2 to lO. ) as a diol component, and a carboxylic acid component consisting of a bivalent or higher carboxylic acid, its acid anhydride, or its lower alkyl ester (e.g., fumaric acid, maleic acid, maleic anhydride, phthalate). Polyester resins co-condensed with terephthalic acid, trimellitic acid, biromellitic acid, etc.) are more preferable because they have sharp melting characteristics.

In particular, in terms of light transmittance with traben, the apparent viscosity at 90°C is 5 x 1 G' to 5 x 1 G' voids, preferably ? ．． ．． 5 x 10' to 2 x 10' poise,
More preferably 1G'N10'poise, ioo
The apparent viscosity at °C is 10'~5 x 10'bois,
Preferably 104 to 3 X 10' poise, more preferably to' to 2 X 10' poise,
Color 100P with good light transmittance is obtained, and even as a full color toner, good results are obtained in fixing properties, color mixing properties, and high temperature offset resistance. In particular, the apparent viscosity P at 90°C,
The absolute value of the difference between the apparent viscosity P2 and the apparent viscosity P2 at 100°C is 2
X 1G'< l PI-P2 1 < 4 X
10' (DffiDIlNial (D is particularly preferred).

The coloring agent used in the present invention includes known dyes and pigments, such as copper phthalocyanine. Insoluble azo, disazo yellow, and anthraquinone pigments. Quinacridone pigment. Disazo oil-soluble dyes and the like can be widely used.

Further, the colorant may be subjected to some kind of surface treatment for the purpose of increasing the affinity between the resin and the colorant.

Particularly preferred pigments include C.I. I. Pigment Yellow l7, C. I. Pigment Yellow 1. C. I. Pigment Yellow 12, C, I. pigment yellow l3
,C. I. Pigment Yellow l4, C. I. Pigment Red 5, C. I. Pigment Red 2, C. I. Pigment Red 3, C. I. Pigment Red l7, C
．． I. Pigment Red 22, C. I. Pigment Red 23, C. I. Pigment Red 122, C. I
．． Pigment Blue l5, C, ■. pigment blue l
6 or imidoalkyl group (in the formula, R represents an alkylene group having 1 to 5 carbon atoms)] as a substituent, or a copper phthalocyanine pigment having the structural formula (I) shown below. Copper phthalocyanine pigments, which are Ba salts having 2 to 3 carboxybenzamidomethyl groups substituted on the phthalocyanine skeleton.

(Hereinafter, blank space) n=2 to 3 As the dye, C. I. Solvent Red 49, C. I
．． Solvent Red 52, (:.I. Solvent Red 109, etc.).

The content of yellow toner, which is sensitive to the transparency of OHP films, is 10% of the binder resin.
0 parts by weight or less, preferably 0.0 parts by weight or less.
5 to 6 parts by weight is desirable.

If the amount is 8 parts by weight or more, green, which is a mixed color of yellow. Red, and as an image, it has poor reproducibility of human skin color.

Regarding the other magenta and cyan color toners 5, 10 parts by weight or less, more preferably 0.1 to 8 parts by weight, per 100 parts by weight of the binder resin! It is desirable that the amount is less than 1 part.

In particular, for black toners that use two or more colorants in combination, adding a total colorant amount of 15 parts by weight or more not only tends to cause svent formation in the carrier, but also exposes a large amount of the colorant on the surface of the color toner. This also increases concerns about toner fusing to the drum and fixing performance. Therefore, the amount of the colorant is preferably 3 to 10 parts by weight per 100 parts by weight of the binder resin.

Preferred combinations of colorants for shaping black toner include a combination of a disazo yellow pigment, a monoazo red pigment, and a copper phthalocyanine blue pigment. The blending ratio of each pigment is yellow pigment. The ratio of red pigment and blue pigment is 1:1.5-2.5:0.5-1
．． 5 is preferred.

A charge control agent may be added to the toner according to the present invention in order to reduce the charging properties. In this case, a colorless or light-colored charge control agent that does not affect the color tone of the color toner is preferred. In the present invention, when a negatively charged developer is used,
The present invention is even more effective in that negative charge control agents include organometallic complexes such as metal complexes of alkyl-substituted salicylic acids (eg, chromium or zinc complexes of di-tert-charybutyl salicylic acid).

When the negative charge control agent is added to the color toner, it is preferably added in an amount of 0.1 to 10 parts by weight, preferably 0.5 to 8 parts by weight, per 100 parts by weight of the binder resin.

As the magnetic particles used in the present invention, for example, surface-oxidized or unoxidized metals such as iron, nickel, copper, zinc, cobalt, manganese, chromium, rare earths, and their alloys or oxides and ferrites can be used. Moreover, there are no special restrictions on the manufacturing method.

In the present invention, the surfaces of the magnetic particles are coated with a resin or the like. Methods for this include a method in which a coating material such as a resin is dissolved or suspended in a solvent and applied and adhered to the magnetic particles, or a method in which a coating material such as a resin is dissolved or suspended in a solvent and then applied to the magnetic particles. Any conventionally known method can be applied, such as a mixing method. In order to stabilize the coating layer, it is preferable that the coating material be dissolved in a solvent.

The coating material on the surface of the magnetic particles varies depending on the toner material, but examples include aminoacrylate resin, acrylic resin, copolymers of these resins and styrene resin, silicone resin, polyester resin, polytetra Fluoroethylene, monochlorotrifluoroethylene polymer, polyvinylidene fluoride, etc. are preferred, but
It is not necessarily limited to this.

The most suitable materials for the present invention are acrylic resins or copolymers of these resins and styrene resins.

The most suitable material for the magnetic particles used in the present invention is
98% or more Cu-Zn-Fe (composition ratio (5-20)
Ferrite particles having a composition of: (5 to 20) : (30 to 80), which can easily smooth the surface, have stable charge imparting ability, and provide a stable coating.

The coating amount of the above compound may be appropriately determined so that the charge imparting properties of the magnetic particles satisfy the above-mentioned conditions, but generally the total amount is 0.1 to 30% by weight (
(preferably 0.3 to 20% by weight).

The weight average particle diameter of these magnetic particles is preferably 35 to 65 μm, preferably 40 to 60 μm. Furthermore,
The weight distribution is 26% or less, and the weight distribution is 3.
A good image can be maintained when the ratio between 5 pm and 43 μm is 5% or more and 25% or less, and the ratio of 74 or more is 2% or less.

In the present invention, good results are usually obtained when the mixing ratio of the above-mentioned magnetic particles and toner particles is 2.0% to 9% by weight, preferably 3% to 8% by weight in terms of toner concentration in the developer. It will be done. If the toner concentration is less than 2.0% by weight, the image density will be too low to be practical, and if it exceeds 9% by weight, fogging and in-machine scattering will increase and the useful life of the developer will be shortened.

In addition, in the present invention, fatty acid metal salts such as zinc stearate, aluminum stearate, etc., or fine powders of fluorine-containing polymers, such as polytetrafluoroethylene, polyvinylidene fluoride, etc., and tetrafluoroethylene-vinylidene are used as lubricants. Fine powder of fluoride copolymer or abrasive such as cerium oxide or silicon carbide,
A conductivity imparting agent such as tin oxide or zinc oxide may be added.

In order to produce the colorant-containing resin particles according to the present invention, the thermoplastic resin may be used as a pigment or dye as a colorant, as necessary.
Charge control agents and other additives are thoroughly mixed using a mixer such as a ball mill, and then melted, kneaded, and kneaded using a heat kneader such as a heated roll, kneader, or extruder to make the resins mutually compatible. Colorant-containing resin particles according to the present invention can be obtained by dispersing or dissolving a pigment or dye in the solution, cooling and solidifying, and then pulverizing and strictly classifying.

Below, each measuring method (1) to (3) related to the characteristic value of the developer used in the present invention will be described.

(1) Particle size distribution measurement: The measuring device is a Coulter counter TA-II type (
Coulter) and an interface (manufactured by Nikkaki) that outputs the number average distribution and volume average distribution, and CX-1.
A personal computer (manufactured by Canon) is connected, and a 1% NaCil aqueous solution is prepared using primary sodium chloride as an electrolyte.

As a measurement method, 100 to 150 mil of the electrolytic aqueous solution
0.1 to 5 mil of a surfactant, preferably an alkylbenzene sulfonate, as a dispersant is added therein, and further 0.5 to 50 mg of the measurement sample is added.

The electrolytic solution in which the sample was suspended was dispersed for about 1 to 3 minutes using an ultrasonic disperser, and the particle size distribution of particles of 2 to 40 μm was measured using the Coulter counter TA-11 model using a 100 μm aperture. Find the volume average distribution and number average distribution.

These volume average distributions were obtained. From the number average distribution, each value of the volume average particle diameter, 6.35 μm or less for the number average distribution, and 16.0 gm or more for the volume average distribution is obtained.

(2) Frictional charge measurement: FIG. 1 is an explanatory diagram of the frictional charge amount measuring device.

First, a mixture of particles to be measured and magnetic particles to be used as a developer is prepared. The mixing ratio is 5 parts by weight to 95 parts by weight of magnetic particles in the case of toner and colorant-containing fine particles, and 2 parts by weight to 98 parts by weight of magnetic particles in the case of a fluidity imparting agent. .

The magnetic particles used in the measurement are those used in two-component developers. For example, ferrite particles coated with styrene resin, 250 mesh pass 40
Contains 70% by weight or more (more preferably 75 to 95% by weight) of 0 mesh particles and is coated with 0.2 to 0.7% by weight of styrene-2-ethylhexyacrylate-methyl methacrylate copolymer. Some examples include:

The particles to be measured and magnetic particles are placed in the measurement environment (23℃
, 60%) and allowed to stand for 12 hours or more, then placed in a polyethylene bottle, thoroughly mixed, and stirred (150 times of back-and-forth mixing).

If the sample is a colored resin powder, a mixture of 5 g of colored resin powder and 95 g of magnetic particles is used. If the sample is a flow improver, a mixture of 2 g flow improver and 98 g magnetic particles is used. Polyethylene bottle is 100mA'
A turbine and a mixer (3 times/second) are used for stirring.

Next, the particles whose triboelectric charge amount is to be measured are placed in a metal measurement container 112 with a conductive screen 113 of 500 mesh (the size can be changed as appropriate to prevent magnetic particles from passing through) on the bottom, as shown in FIG. A mixture of magnetic particles and magnetic particles is put in and a metal lid 114 is placed. The weight of the entire measuring container 112 at this time is weighed and is defined as wl (g). Next, suction is carried out through the suction port 117 in the suction device ll (at least the portion in contact with the measurement container 112 is an insulator), and the air volume control valve 116 is adjusted to set the pressure on the vacuum gauge 115 to 250 mmAq. In this state, suction is performed sufficiently (for about 2 minutes) to remove the toner. Let V (volt) be the potential of the electrometer 119 at this time. Here, 118 is a capacitor whose capacity is C (p
F). Also, weigh the entire measurement container after suction.
2(g). This amount of triboelectric charge T (ILc/g)
is calculated as shown below.

(3) Moisture Content Measurement A generally known heating dry gravimetry method was employed to measure the moisture content of the alumina particles. As the measuring device, an electronic moisture meter PDa-300WMB was used, and the drying conditions were set at a temperature of 150° C. and 10 minutes in the moisture content timer measurement mode.

Low temperature and low humidity (15℃, 10%) High temperature and high humidity (32
．． Weigh out approximately 2 g of alumina particles that had been left at 5°C (85%) into a flat weighing bottle (inner diameter 50 mm) with a known weight, spread the sample so that it has an almost uniform thickness, and Accurately weigh the weighing bottle. lO at set temperature 150℃
After heating and drying for a minute, weigh the weight to determine the amount of weight loss.
Calculate the water content (weight %) using the following formula.

? In the study, in order to determine the saturated water content under each environment, alumina particles were left in each environment for 1 day, 3 days, 5 days, and 10 days, and the number of days until the water content reached saturation was examined. As a result, it was confirmed that there was almost no difference in water content between the product left for 3 days and the product left for 5 days, and the value hardly changed even after being left for 10 days. Therefore, it was assumed that the product was left in each environment for 10 days to reach a sufficiently saturated water content, and the saturated water content was defined as the water content of a product left in the environment for 10 days.

In addition, when considering wood, the moisture content QH of products left under high temperature and high humidity
It has also been confirmed that QL always shows a larger value than the moisture content QL of products left under low temperature and low humidity.

Ql,<QH [Example] The basic structure and features of the present invention have been described above.
The method of the present invention will be specifically described below based on Examples. However, the embodiments of the present invention are not limited in any way by these. All parts in the examples are parts by weight.

Example 1 was sufficiently premixed using a Henschel mixer, then melt-kneaded twice using a three-roll kettle, cooled, and coarsely ground to a particle size of about 1 to 2 mm using a hammer kuru. Then, it was pulverized using an air jet type pulverizer. Furthermore, the obtained finely ground material was classified using a multi-division classifier to obtain colorant-containing resin particles.

The water content of the alumina particles measured by heating loss measurement method was added to 100 parts of the above colorant-containing resin particles under low temperature and low humidity (15°C, 10°C).
%) QL is 3.1% when left for 10 days, and moisture content QH when left for 10 days under high temperature and high humidity (32.5℃.85%)
is 5.8%, and the specific surface area by BET method is 96m"
0.3 parts of Alyona particles (electrostatic charge -2 μc/g) obtained by the gas phase method and silica fine powder with a specific surface area of 250 m27 g by the BET method and hydrophobized with hexamethyldisilazane. Body (charge amount -80μc/g)
A total of 0.5 part was added externally to prepare a cyan toner.

Cu surface-coated with styrene-acrylic acid-methacrylic 2-ethylhexyl copolymer was added to 6 parts of this cyan toner.
-94 parts of Zn-Fe type ferrite particles were mixed to prepare a developer.

The amount of charge of this toner in a low-temperature, low-humidity environment (15°C, 10% RH), and in a high-temperature, high-temperature environment (32.5°C, 85% RH)
The amount of charge in is shown in Table 2.

Using this developer, a commercially available plain paper color copying machine (CL
C-500 (manufactured by Canon), a running test of 30,000 sheets was performed at room temperature (23℃.60%), low temperature and low humidity (1
As a result, high-quality images with sufficient image density were obtained in both environments.

Example 2 Alumina particles obtained by the wet method in Example 1 (QL = 4.5, Q}I = 6.1%, BET
Specific surface area by method is 126 m'/g, charge amount Oac/
g) Images were produced in the same manner except that 0.3 parts were used, and images with sufficient image density and high quality were obtained even under low temperature and low humidity, and there was no fogging even under high temperature and high humidity. A sharp image was obtained.

Comparative Example 1 In Example 1, QL=3.6%. QH = 11.5%
Alumina particles (specific surface area t4am”/g in BET
), the effect of suppressing excessive charge amount by adding alumina particles was more pronounced under high temperature and high humidity, and the same image as Example 1 was obtained under low temperature and low humidity. Although images with high density and high quality were obtained, under high temperature and high humidity conditions, toner scattering due to insufficient charge was noticeable.

Comparative Example 2 A cyan toner was prepared in the same manner as in Example 1 except that the alumina particles used were doubled from 0.3 parts to 0.6 parts. In this case, too much toner was applied, and toner scattering became noticeable under high temperature and high humidity conditions.

Comparative Example 3 When an image was produced in the same manner as in Example 1 except that no alumina particles were added, a poor image with a particularly high charge amount and low image density was obtained under low temperature and low humidity conditions.

When a toner with a fine particle size is used as in the present invention, an external additive such as Aloyna particles which functions to suppress an excessive charge amount is essential.

Example 3 In Example 1, QL=6.8%. Q+ -13.2%
alumina particles (specific surface area 290 m”/g by BET)
After hydrophobizing with silicone oil, images were imaged in the same manner as in Example 1 except that this was externally added. When externally added at a prescribed amount of 0.3 parts, the concentration was slightly lower under low temperature and low humidity. Although it was thin, the above problem was solved by simply increasing the amount of alumina particles added to 0.4 parts, and sharp images without fogging became possible. Moreover, there were no problems at all even under high temperature and high humidity conditions. Furthermore, no deterioration of the agent was observed even after running 30,000 sheets.

Comparative Example 4 Imaging was carried out in the same manner as in Example 3, except that the alumina particles (QL = 6.8%, Q, = 13.2%) that were not subjected to the hydrophobization treatment in Example 3 were used as they were. As a result, even if the amount of alumina particles added was reduced to 0.2 parts, the amount of charge under high temperature and high humidity conditions was insufficient, and toner scattering occurred during durability. However, no particular adverse effects were observed under low temperature and low humidity conditions. In the case of alumina particles having a small primary particle diameter such as those used in Example 3 or Comparative Example 3, the toner surface properties of the alumina particles are greatly improved, and the toner particles greatly function to suppress excessive charge amount. In addition, the increase in specific surface area generally leads to a higher water content, further promoting the above-mentioned effects. Therefore, some kind of hydrophobization treatment is effective for alumina particles having a small particle size, and this improves the charging characteristics of the toner.

Example 4 In Example 1, CI Pigment Red 122 was added to 4.5
Magenta resin particles were obtained in the same manner as in Example 1, except that 50% of magenta resin particles were used. 14.5% of Q was added to 100 parts of the colorant-containing resin particles. Q
Alumina particles with H=6.1% (specific surface area by BET method 126 m"/g, charge amount Oac/g) 0.2
1 part and 0.5 part of the fine silica powder used in Example 1 were added externally to prepare a magenta toner.

95 parts of the coat carrier used in Example 1 were mixed with 5 parts of the magenta toner above to prepare a developer, and the same amount of 30,000 parts was prepared as a developer.
Even in the durability test of 30,000 sheets and 0 sheets, stable images were always maintained and high quality images were obtained without any major density changes.

(The following is a blank space) [Effects of the Invention] As described above, according to the present invention, high-quality images can be stably provided for a long period of time in any environment.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an apparatus for measuring the amount of triboelectric charge in the present invention.

Claims (3)

[Claims] (1) A color toner containing at least non-magnetic colorant-containing resin particles containing a polyester resin as a binder resin and an external additive, the color toner containing at least alumina particles B as the external additive; Particle B has a saturated water content Q_L of 1.5% by weight or more at temperature/humidity = 15°C/10% and a saturated water content Q_H of 1 at 32.5°C/85%.
2% by weight or less, and the ratio of Q_H and Q_L is Q_H/Q_
L≦3, and the specific surface area S_B according to the BET method is 3
A color toner characterized in that it has a density of 0 to 300 m^2/g. (2) Absolute value of frictional charge amount with magnetic particles is 50μc/g
With the above, the specific surface area S_A by BET method is 80m^2/g
A claim characterized in that it contains at least two kinds of inorganic oxides: the above-mentioned hydrophobic inorganic oxide A and alumina particles B whose absolute value of triboelectric charge with magnetic particles is 20 μc/g or less ( 1) Color toner described. (3) Hydrophobic inorganic oxide A for colorant-containing resin particles
Claim (1) characterized in that it contains at least a% by weight of alumina particles B and b% by weight of alumina particles B, and satisfies a≧b, 0.3≦a+b≦1.5, and S_A≧S_B. and the color toner described in (2).